when you think you have pumped all you have strength to do, close your bleeder tight, crank you handlebar to the extreme left and tie the brake lever back. Leave it over night. All the little bubbles will work their way up to the reservoir and will sponge up ur brakes no more!
That's an old racer trick to make the brakes as sensitive as possible, and it lasts for about one race. There's no bubbles rising to the top, air being absorbed by the fluid, etc. But it does make the lever have less travel and
appear to be firmer. So folks have invented all sorts of reasons for themselves as to what's happening.
Disc brakes are self-adjusting. You squeeze the lever, and rather than sliding through the piston seal, the brake piston distorts that seal slightly as it moves toward the rotor. Release the brake lever, and the rubber piston seal is what pulls the piston back away from the rotor as it returns to its original shape. If there's excess clearance between the pad and rotor before you apply the brake, the seal will reach its limit of distortion and allow the piston to slide through slightly - that's the auto-adjustment. When you apply the brake firmly and tie off the lever over night, you're simply allowing the seal time enough to relax and slide back over the piston without retracting it. This puts the pads in very close contact to the rotor with the lever released, so lever free play is almost nil. This feeling won't last more than a couple hundred miles, as pad wear returns the lever free play to normal.
Stu
